As further advances have been made in progress toward higher integration of a semiconductor device, a device structure has undergone further miniaturization, and has turned more multilayered, thereby rendering the structure more complex. In order to enhance yield in a process for manufacturing the semiconductor device, there is the need for a technology for detecting an electrical defect such as a conduction deficiency, and so forth, directly connected with a semiconductor device deficiency, with high sensitivity. Defects of which detection is required have since undergone diversification to include an exposure pattern deficiency in a resist pattern, conduction deficiency of a contact hole, deficient embedding of a plug, alignment deficiency at the time of stacking, and so forth. There is available a defect inspection technology making use of an electron beam, capable of meeting the need in the process for manufacturing the semiconductor device. With the defect inspection technology, when electron beams are caused to converge, and scan over a semiconductor wafer, secondary electrons emitted from the wafer are detected to thereby acquire a secondary electron image of a circuit pattern. For detection of a normal part, and a defect part, advantage is taken of electrostatic charging of a semiconductor wafer, occurring when the semiconductor wafer is irradiated with the electron beams. Because there occurs a difference in an amount of static charge between the normal part, and the defect part, and a detection amount of the secondary electrons undergoes a change, a contrast between the normal part, and the defect part can be obtained. This contrast is called a defect contrast.
As a method for achieving enhancement of the defect contrast, thereby performing inspection with high sensitivity, there haven been known various methods including a method whereby a voltage is applied to an electrode for controlling static charge, provided on a semiconductor wafer, to thereby control polarity of the static charge, and an amount of the static charge by use of secondary electrons occurring when the semiconductor wafer is irradiated with electron beams, and a method whereby a wafer is electrostatically charged in advance by use of an electron source capable of irradiating a large area at a large current, and thereafter, inspection is performed by use of electron beams for the purpose of the inspection. For example, in the case where a surface of a wafer is positively charged, secondary electrons emitted from the bottom of an open contact hole are drawn out by positive static charge of the surface. The open contact hole in the normal part will turn brighter than an insulating film on the periphery of the open contact hole, so that a pattern contrast can be formed.
On the other hand, in the defect part where a portion of the insulating film is left out at the bottom of the open contact hole, the insulating film at the bottom thereof, as well, is positively charged as is the case with the surface of the wafer, so that an electric field drawn out from the bottom will be weakened. A non-open contact hole will be as bright as the insulating film on the periphery of the non-open contact hole, and a difference in brightness between the normal part, and the defect is the defect contrast.
Meanwhile, as a method for achieving enhancement of the defect contrast by use of a static charge control technology without the use of an electron beam, there has been known Japanese Patent Application Laid-Open Publication No. 2003-151483 (Patent Document 1). In the case of inspecting non-conduction deficiency of a plug in a semiconductor wafer including a transistor such as a CMOS, and so forth, a junction part formed between a p-type semiconductor, and an n-type semiconductor, incorporated in the semiconductor wafer, will pose a problem. With the method for controlling static charge by use of an electron beam, an amount of the static charge will undergo a change according to a resistance value of a device, so that it has been necessary to change over the polarity of a voltage to be applied to an electrode for controlling static charge according to the type of junction, thereby obtaining a pattern contrast. Furthermore, there has existed another problem that variation in resistance value at a junction will lead to variation in pattern contrast of the plug, thereby resulting in deterioration of the defect contrast.
In Patent Document 1, there is shown a method whereby resistance at a junction is lowered by irradiating a junction layer with ultraviolet light to thereby enhance a pattern contrast. The ultraviolet light makes use of a wavelength transmitting through an insulating film to be absorbed by Si. The ultraviolet light for irradiation transmits through the insulating film formed on the wafer to reach an Si-layer. As the ultraviolet light absorbed by the Si-layer creates electron and hole in pairs at a junction part to thereby render the unction par electrically conductive, resistance is lowered. Since resistance at junction is negligible, it is possible to obtain a uniform pattern contrast regardless of the type of a junction. Furthermore, since variation is negligible due to reduction in resistance at the junction part, the pattern contrast is stabilized, and therefore, a defect inspection with high sensitivity can be performed.